Innate immune responses are central to the pathogenesis of atherosclerotic cardiovascular disease and are orchestrated through transcriptional networks involving epigenetic modification of the chromatin architecture. There is now increasing evidence that the chromatin state is affected by telomerase. In addition to its well- established function to synthesize telomere repeats at the ends of chromosomes, telomerase reverse transcriptase (TERT) serves a direct role in facilitating the activation of gene expression programs. This second activity of TERT in permitting gene transcription appears to operate independently of its role in telomere homeostasis but may involve modification of the higher-order chromatin structure. Although TERT is expressed in macrophages of human atherosclerotic lesions, a physiological role of this non-canonical activity of TERT in inflammation and atherosclerosis remains to be discovered. Our recent studies confirmed that TERT activates gene promoters in macrophages. Conversely, TERT-deficiency alters macrophage inflammatory gene expression by inducing chromatin modifications reminiscent of gene silencing. Two specific aims are proposed to explore the significance of these findings and to test the hypothesis that TERT promotes inflammatory gene expression in macrophages through epigenetic chromatin modifications and contributes to the development of atherosclerosis. In Specific Aim 1 we will utilize a combination of cellular and molecular approaches to determine the transcriptional mechanisms by which TERT regulates macrophage inflammatory gene expression programs. In Specific Aim 2 we will determine the contribution of TERT to the development of atherosclerosis and test the hypothesis that TERT-dependent activation of inflammatory gene expression in macrophages constitutes an important mechanism for the development of the disease. Ultimately, the results of these studies will not only characterize TERT as a chromatin modifier and novel regulatory protein orchestrating macrophage inflammatory gene expression but also advance our understanding of the inflammatory mechanisms contributing to the development of atherosclerosis. PUBLIC HEALTH RELEVANCE: Atherosclerotic cardiovascular disease is the leading cause of death in the United States, and inflammatory pathways contribute to all stages of the disease. This application will investigate novel mechanisms that control the activation of inflammation during atherosclerosis formation. The results of these studies may ultimately characterize novel pathways contributing to vascular diseases and lead to new therapeutic opportunities.